1. Field of the Invention
The present invention relates to an oily ink, particularly an oily ink designed for writing instruments. The present invention relates to a gel-type oily ink which can be suitably used for correction tools including correction pens, oil-type ball-point pens, paint markers and the like.
2. Description of the Prior Art
Heretofore, as an oily ink for writing instruments, paint markers using aluminum powder pigments, correction pens containing titanium dioxide, and the like have been proposed. In addition, with regard to the oily ink, there are various types of constructions for the correction pens, including pen-types, bottle-types with brush coatings, and the like. These types share the common characteristics of having a stirrer made of a metallic ball built in the container in order to redisperse the colorants by stirring the ink itself. That is, in the conventional paint markers or ball-point pens, when they are left in a settled state, colorants including aluminum powder pigments or titanium dioxide settle in the ink within the container and the functions as paint markers or ball-point pens cannot be fully realized. Therefore, it has been necessary for the users to redisperse the colorants that settle and separate in the container, in order to restore the initial disperse state.
Japanese Unexamined Patent Publication No. 6-264012 proposes a correction fluid compounding montmorillonitexe2x80x94type clay mineral in order to prevent the sedimentation of the colorants as an opacifying agent and maintain the redispersibility of the system. Japanese Unexamined Patent Publication No. 7-173417 proposes a correction fluid compounding a fluorine metallic mica.
However, in the case of such conventional oily ink compositions, sedimentation layers are sometimes formed at the bottom of the ink when left in a settled state for a long period of time although the compositions prevent the colorants from settling as much as they can. Therefore there is little difference from the conventional oily ink in that redispersion has to be considered. Moreover, and in particular, when the clay mineral or fluorine metallic mica is compounded beyond a certain level for thickening the viscosity, the ink compositions have become gel-type, thereby making it impossible to obtain smooth coated films when coating. Regarding this point, the same thing can be said about an oily ink composition used for oil-type ball-point pens or paint markers as well as correction tools including correction pens and the like, and the provision of such an oily ink as can prevent sedimentation of the colorants while maintaining writing performance is desired in that field, too.
Further, in conventional oil-type ball-point pens, particularly in ball-point pens using a white-colored oily ink, like general ball-point pens using a black-colored ink, solvents with high boiling point are used, thereby causing the problem of not drying when writing with such an ink on a non-absorbent surface although when writing on an absorbent surface like that of paper and the like, drying can be seen only apparently. Moreover, the fact is that the fluidity is very bad and has no practicality in coating on a surface, especially thickly on a surface.
It is, therefore, desirable to provide an oily ink composition that is not inclined to sedimentation and that dose not necessitate redispersion of its components. This is desirably provided by an oily ink for writing instruments comprising
a. a colorant,
b. a resin,
c. an organic solvent and
d. a gelling agent,
wherein the said gelling agent comprises a soluble gelling agent with a solubility of from about 0.1 to about 20% by weight at the temperature of 20xc2x0 C. to the said organic solvent, and the viscosity of the ink is not less than 700 mPaxc2x7s when the rate of shear is 0.1(1/s) and not greater than 500 mPaxc2x7s when the rate of shear is 100(1/s)